- use asm_tester instead of data variable name
- directly expose Variable and Label for convenience

Change-Id: I211fe07e236f96067037ca00c1435c1491121e6b
Reviewed-on: https://chromium-review.googlesource.com/574914
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46738}